Nozzle channel construction



Nov. 30, 1937. G. scHAPER NOZZLE CHANNEL CONSTRUCTION Filed April 20, 1935 Hwa/vra@ G50/PG SCHH/DER 5r f 24M /1 Tram/Er Patented Nov. 30, 1937 UNITED STATES PATENT OFFICE Georg Schaper, Muelhem-Ruhr-Broich, Germany, assignor to Ho lzwarth Gas Turbine Co.,

San Francisco, Calif., a corporation of Dela- Ware Application April 20, In Germany 8 Claims.

The present invention relates to an improved construction of the nozzle or nozzles connected with the discharge end of the explosion chambers of explosion gas turbines, and particularly to constructions in which aplurality of explosion chambers discharge into a common nozzle construction containing a single nozzle or a plurality of individual nozzles.

The construction and arrangement of the noz- 10 zle channel, that is, the passageway leading from the outlet or nozzle valve at the discharge end of an explosion chamber of an, explosion turbine to the inlet end or ends of the nozzle or nozzles associated therewith, have caused considerable difiiculties even when each explosion chamber is provided with its own individual multiple nozzle structure. For on the one hand the walls of the nozzle channel must withstand the shock and strain of very high sudden gas pressures upon the interior thereof and also the more or less constant pressure of the cooling agent from the outside thereof, while on the other hand they are subjected' to very great temperature stresses, the cooling agent pressure being in most cases made very high in order to ellect removal of heat at high temperature ranges and thus make possible an economical utilization of the abstracted heat; in addition, there exists the further requirement that the size of the nozzle channel be kept as small as possible in order to reduce to the smallest possible degree the transfer of heat to the walls of such channel. These diiilculties are aggravated when, according to more recent proposals, a plurality of explosion chambers are made to operate upon a, common nozzle or group 'of nozzles: for in such case not only is the size of the nozzle channel necessarily increased, so that a certain increased heat loss must be taken into account with the simpliiication of the con- 40 struction, but above all the heat transfer is increased because, the combustion chamber size and the cycle frequency remaining the same, the quantity of gases discharged into the nozzle channel per unit of time is multiplied corresponding to the number of explosion chambers connected to the common nozzle channel. The known methods of building the nozzle channel cannot adequately take care of the high temperature stresses which resultv under these new conditions, particularly with the wall thicknesses heretofore employed. If the stresses are to be reduced to a permissible magnitude by reducing the thickness of the walls (and in this connection the wall thicknesses under present day conditions can ce estimated at a maximum of 8 mm.) ,then the ar- 1935, Serial No. 17,467 April 23, 1934 (ci. sli-41,)

rangement and construction of the nozzle channel as heretofore suggested must be abandoned if the nozzle channels are to withstand, with the reduced wall thicknesses, the very great gas pressure upon one side and the cooling agent pressure upon the other side.

It is accordingly an object of the invention to provide a nozzle channel construction for leading the hot, high pressure explosion gases of one or more constant volume explosion chambers to a nozzle assembly, the nozzle channel being constructed to withstand high internal and external pressures while at the same time dangerous temperature stresses are avoided. It is also an object of the invention to provide a nozzle channel construction wherein a nozzle channel built of relatively thin walls is elastically suspended wit-hin a jacket or casing of relatively thick walls in such a manner that the channel can expand and contract in correspondence with rise and fall of the temperature of its walls, so that such walls can readily adapt themselves to the uctuating temperatures and pressures to which they are subjected during the normal operation of an explosion turbine.

In accordance Vwith the present invention there is provided a construction for the nozzle channel and nozzle or nozzles of explosion chambers, such as are particularly suited for explosion turbines, in which a plurality of chambers discharge into a common individual nozzle or common group of nozzles, such construction being characterized by the fact that themember which forms the nozzle channel lying between the nozzle valve and the nozzles is constructed in the form of an elongated thin-walled tube and is surrounded by afcooling space. Such a tube is inherently pressure-proof; in addition the external cooling agent pressure can operate uniformly on all sides thereof and so equalizes itself, so that a suiiiclent mechanical strength against buckling of the tubular body is attained even with small wall thicknesses because, in spite of the manifold increase in the heat transfer, no dangerous temperature stresses occur since the temperature drop through the Walls is reduced as the wall thickness is reduced.

Other objects of the invention will appear from the following description and the features of novelty are set forth in the appended claims.

The invention will be further described with the aid of the acompanying drawing which illustrates an embodiment of the invention by way of example. In said drawing:

Fig. 1 represents a longitudinal section through a nozzle construction in accordance with the in- `vention and is taken along the line I-I of Fig. 2, the View being developed in the plane of the drawmg;

Fig. 2 shows a partial longitudinal section through the nozzle structure, according to line .li-EI voi Fig. 1;

Figs. 3 and 4 show respectively cross sections along the lines III- III and IV-IV of Fig. 1; y

Fig. 5 is a partial view in elevation of the inner tubular body, looking in the direction of the arrow a of Fig. i;

Fig. 6 shows on an enlarged scale a detail of Fig. B;

Fig. 7 is a cross sectional view on an enlarged scale through the end of the nozzle, and

Fig. 8 shows on an enlarged scale the construction of the elastic ring connections between the inner tubular body and the outer jacket member.

Referring to Fig. 3 the rotor of the combustion gas` turbine is shown at l, the nozzle. structure in accordance with the invention being shown in transverse section. The rings of rotor blades are shown at 2 and 3, while the housing is indicated at 4. As is. well understood in the art, the nozzle structure is connected with the discharge end of an explosion chamber, the outlet or nozzle valve of such chamber being shown at 5 in Fig. 1, such valve being arranged to open into an enlargement 'l of a tubular member 6. In the closed position the valve engages a seat 5a. This tubular member may, in accordance with the invention, be

' made to provide the common nozzle channel for two explosion chambers whose nozzlek valves are received in the tulip-shaped enlargements 1 at the opposite ends of such member. As can be seen from Figs. l and 2 the shape of the tubular member 6 is so determined that onthe one hand the mouths of the nozzles connected therewith (see especially Fig. 2) lie upon the surface of a cylinder concentric with Ithe rotor axis, while on the other hand the tulip-shaped enlargements 1 are l displaced from a plane parallel to the turbine rotor plane, so that they lie outside of the' rotor' housing 4.

The tubular'member 6 carries connections d one behind the other in the longitudinal portion lying between the two enlargements i, the ends of such connections lying in a plane 9, 9 which is parailel to the rotor plane I0, I0. These connections preserve the breaking strength of the tubular member 6 in spite of the slitting provided for the gas outlet, and may be cast integrally with the member 6, such connections acting to connect the upper and lower portions of the member 6 (Figs. 3, (i, and 6). The inlet sections of the nozzles i2 are attached to the connections 8, for example by welding at the points 9a. The nozzles i2 with their inlet sections Il are made of a single piece, but they may be composed in known manner of a number of parts connected together, for example, by. welding. In each case the nozzies are completely machined prior to welding to the connections 8, and in particular they are cornpletely smoothed down on their interior gasswept surfaces. l

.As shown in Fig. 7, there are provided slit-like cut-outs i3 at the discharge end of each of the nozzles, such cut-'outs forming channels for the cooling agent after the assembly of all of the nozzles' with the tubular member 6 and after the welding at the points i4 is completed, so that a cooling agent can penetrate to the ends of the walls defining the nozzle outlets during the operation oi the turbine and thus c0011 such Walls.

ascenso By virtue of their tubular shape the walls of the parts 6, l, and 8 can be made very thin without loss of strength against internal and external super-pressures. The small wall thickness causes .welded joints I8 after inserting and securing the parts G, i, il, and i2. The securing of the parts l, "i, 8, il, and l2 within the member i5 of the cooling jacket is effected by way of the elastic rings I9, which are attached to the flanges 20 of the cooling jacket member i5 on the one hand, and at the ends of the enlargements 'l on the other, for example by welding, as can be seen from Figs. l and 8. The united cooling jacket `parts I5 and I6, as can be seen from Figs. 3 and 4, likewise form a tubular member which is capable of suilicient resistance to the mechanical stresses resulting from the cooling agent pressure. The tubular form is interrupted only by the connections 8, which penetrate the cooling jacket part I6, or by the nozzle inlet sections Il. At this place the strength of the cooling jacket against the inner pressure can however be increased by employing staybolts 2l whose threaded portions 22 are received in the' nipples 23 oi the part I6 of the cooling jacket. IThe part I6 is connected with the outlet ends of the nozzle by means of a thin elastic wall 24 which is arched outwardly to increase its elasticity. This wall 24 is connected laterally with the nozzle ends and is also radially connected with the two end nozzles, as by the vwelded joints 25, as can be seen from Figs. l, 3, 4 and especially Fig. 6. The inner member composed of the tubular body 6, the enlargements i, the connections 81, the nozzle inlet sections l I and the nozzles i2 is thus held within the outer body l5, i6 on the one hand by the elastic rings and on the other by the elastic walls 24. In consequence of this elastic suspension the whole inner body is free to expand relatively to the outerbody, since during i the operation of the turbine it assumes much higher temperatures than the outer body.

The ilanges 26 hold the jacket members i5, i6 rigidly against the turbine housing d; while the flanges 2G oi the jacket member l5 are attached to the housings of the nozzle valves 5.

The explosion chambers referred to hereinabove are of the constant volume type employed vsion chamber, an outlet valve at the discharge end of the chamber'controlling the 'communication between such chamber and the nozzle channel, the walls of said channel being relatively l atively thin assembly, said channel and spaced therefrom to provide- 'a cooling eral passageways leading into the nozzle essembly, a relatively thick walled jacket about said and spaced therefrom to provide a-cooling chamber adapted to receive a current of agent. the jacket being connected to said between said channel and said jacket for elastically suspending the channel within the relatively rigid jacket for enabling the channel to expand and contract as the temperature of its walls and the pressure thereon vary.

2. In a constant volume explosion turbine plant, the combination of two constant volume for directing the gases generated in said chambers against a turbine rotor, a nozzle channel in advance of the nozzle assembly and lying between the outlet ends of said explosion chambers, outlet chambers opening approximately endwiser into said channel. the walls of said channel being reland being provided with one or passageways leading into the nozzle a relatively thick walled jacket about more lateral chamber adapted to receive a current of cooling agent, the jacket being connected to said channel to seal the cooling chamber, and elastic connections between the ends of said channel and the said Jacket for elastically suspending the channel within the relatively rigid jacket for enabling the channel to expand and contract as the temperature of'its walls and the pressure thereon vary.

3. '111e combination as set forth in claim 2, wherein the nozzle channel is in the form of a generally tubular member, the ends of said tubular member being enlarged to receive the heads of the outlet valves, and the nozzleassembly belng attached to said tubular member between said enlargements.

valves at the discharge ends of said plurality of constant. volume 4. 'I'he combination as set forth in claim 2. wherein the lateral passageways are formed by tubular ,extensions integral with the channel and terminating .in approximately the same plane, said nozzle assembly being attached to said tubular extensions.

5. 'I'he combination as set forth in claim 2, wherein the jacket is composed of a section overlying the part of the vchannel remote from the nozzles, and two sections connected to the rst section and to the upper and lower edges of the discharge end of the nozzles.

. 6. 'I'he combination as'set forth in. claim 2, wherein the nozzles are formed by hollow walls whose interiors communicate with the cooling jacket above and below such walls.

7. Ihe combination as sety forth in claim 2, wherein the elastic connections between the nozzle channel and the jacket comprise elastic rings of U-shaped cross-section, the lines of connection with such rings being located adjacent to the seats of the outlet valves. f

8. 'I'he combination with the outlet valves of a explosion chambers of an explosion turbine, and a nozzle assembly for directing the gases generated in said chambers against a turbine rotor, of a nozzle channel leading from said valves to said nozzle assembly and comprising a thin-walled tubular member of substantially circular cross-section whose axis is arranged approximately parallel to the plane of the rotor, a jacket about said tubular member and spaced therefrom to provide a cooling space about such member, said jacket being made of a plurality Vof parts and being for the greater part of tubular shape to conform to the shape of said tubular member, and elastic arched walls connecting the cooling jacket with the outlet ends of the nozzle assembly.

GEORG SCHAPER. 

